As someone else posted, SpaceX lists their prices to launch things into space. Your software situations are more complex?
A house construction contractor doesn't have a price list for the sake of obscuring prices, nor because house construction is more complex than space flight.
It's because houses are custom and thus prices are too variable to list in any meaningful way.
For a SaaS product with significant custom integration work, it seems reasonable that prices might also vary in the same way.
If I can tell in advance whether your SaaS product costs $10/seat/mo or $100/seat/mo, I'll probably feel more comfortable asking whether the custom integration work will cost $50k or $100k.